This invention relates to compositions of water soluble polymers and a method of improving their dispersibility in water.
Water soluble polymers are conventionally utilized in the form of dilute aqueous solutions. Although the polymers as manufactured can be dispersed in water to provide homogeneous solutions, care must be exercised in achieving an initial dispersion of the polymer in water. Unless proper precautions are taken, the polymer is likely to agglomerate upon wetting with water to form partially hydrated agglomerated polymer which is slow to dissolve. Moreover, the agglomerated polymer has a tendency to plug liquid handling equipment. Although complete dissolution of the agglomerated polymer is possible its achievement may require extended periods of time or special treatments to promote rapid dissolution of the gels. Removal of the agglomerated polymer from solutions is also an alternative but is wasteful of polymer. Accordingly, much effort has been spent by the skilled artisans to improve the dispersibility of water-soluble polymers in water.
U.S. Pat. No. 4,735,659 teaches coating of water-soluble polymers with hydrophobic fumed silica to improve the water dispersibility of the polymer. The coating is said to be effected by simply blending the water-soluble polymer with the hydrophobic fumed silica.
U.S. Pat. No 4,671,823 discloses that cellulose ethers are effective bulk laxatives which are administered in the form of tablets, as powders or as suspensions. The disadvantages of these forms of administration are discussed in these patents, as well as the need to provide a cellulose ether composition which is palatable and which is administered without the formation of significant amounts of lumps or gels. In order to solve the problem of lump and gel formation U.S. Pat. No. 4,671,823 teaches a process wherein powdered cellulose ether is mixed with hot sucrose syrup until an evenly moist product is formed which is then dried and milled. The amount of sucrose is 20-90 percent of the weight of the resulting encrusted particle.
U.S. Pat. No. 5,266,334 discloses water-dispersible sugar-free bulk laxative compositions which comprise a dry mixture of a) an edible, water-soluble cellulose ether having efficacy as a bulk laxative, b) a sugar-free sweetening component and c) a dispersing agent. A preferred dispersing agent is maltodextrin.
U.S. Pat. No. 4,321,263 discloses the use of psyllium as a bulk laxative. It discusses the tendency of psyllium to form lumps in water and the use of sugar as a means of promoting dispersion ease. The U.S. patent teaches that psyllium powder is rendered rapidly dispersible in water by wetting the psyllium particles with an alcoholic solution of polyethylene glycol or polyvinylpyrrolidone and granulating the thus-coated particles.
Although the above-mentioned methods improve the water dispersibility of water-soluble polymers it would be desirable to further improve their water dispersibility. It would be particularly desirable to improve the water dispersibility of water-soluble polymers without substantially increasing the amount of a dispersing agent, such as maltodextrin or sucrose, or to reduce the amount of a dispersing agent, such as maltodextrin or sucrose, without substantially decreasing the water dispersibility of water-soluble polymers.